1. Field of the Invention
The present general inventive concept relates to an image forming apparatus using a process cartridge, for example, a photocopier, a printer and a multi-function office machine, and more particularly, to a driving gear device to drive a photoconductive drum of the process cartridge.
2. Description of the Related Art
In a process cartridge, processing units, such as an electrifying device, a developing device and a cleaning device, are mounted together with a photoconductive medium as a cartridge to be detachably mounted into a main body of an electrophotographic image forming apparatus. Alternatively, the process cartridge may comprise the photoconductive medium together with at least one of the processing units, such as the electrifying device, the developing device and the cleaning device, as the cartridge for detachable connection to the main body of the electrophotographic image forming apparatus.
An image forming apparatus employing an electrophotographic process uses the process cartridge. Due to easy management and operation without requiring a dedicated skill, the image forming apparatus using the process cartridge has been widely spread.
FIG. 1 is a perspective view illustrating an exterior of a conventional process cartridge. A photoconductive drum 20 is rotatably supported at a cartridge frame 10 by a shaft 21. A photoconductive drum gear 22 is mounted on the shaft 21. Ends of the shaft 21 are protruded by a certain length out of the cartridge frame 10.
FIG. 2 is a view illustrating a connection between the photoconductive drum gear 22 of the conventional process cartridge mounted to a main body (not shown) of an image forming apparatus and a photoconductive drum driving gear 30 mounted to the main body (not shown).
A mounting rail 40 has a photoconductive drum center fixing part 41. By seating the shaft 21 in the photoconductive drum center fixing part 41, the process cartridge is mounted at a desired position in the main body of the image forming apparatus. The photoconductive drum driving gear 30 transmits power from a driving source (not shown) connected to the photoconductive drum driving gear 30 to the photoconductive drum gear 22 by meshing with the photoconductive drum gear 22.
FIG. 3 illustrates a conventional structure of the photoconductive drum driving gear 30. The photoconductive drum driving gear 30 rotates in connection with the driving source and, as shown in FIG. 2, is disposed at a certain angle (a) with respect to a vertical line C of the photoconductive drum center fixing part 41 to apply a force in a certain direction to the process cartridge when transmitting the power from the driving source to the photo conductive drum gear 22 of the process cartridge by meshing with the photoconductive drum gear 22.
When mounting the process cartridge into the image forming apparatus, the photoconductive drum driving gear 30 is at the certain angle (a) with respect to the vertical line C of the photoconductive drum center fixing part 41, and teeth of the photoconductive drum gear 22 mesh with teeth of the photoconductive drum driving gear 30. At this time, the photoconductive drum driving gear 30 is restrained from rotating due to connection with the driving source, such as a motor, and this may cause a problem in that the photoconductive drum gear 22 and the photoconductive drum driving gear 30 may not correctly mesh with each other. That is, the teeth of the photoconductive drum gear 22 and the teeth of the photoconductive drum driving gear 30 may not be properly aligned to mesh when the process cartridge is mounted into the image forming apparatus. Therefore, the teeth of the photoconductive drum gear 22 and the photoconductive drum driving gear 30 can be damaged, thereby deteriorating image quality in the image forming apparatus.
In addition, when the photoconductive drum gear 22 and the photoconductive drum driving gear 30 are incorrectly meshed, the photoconductive drum gear 22 and the photoconductive drum driving gear 30 may operate in a state in which the shaft 21 is deviated from the photoconductive drum center fixing part 41 of the mounting rail 40, as shown in FIG. 2. This may also considerably deteriorate the image quality, and the driving source may be applied with a load, thereby causing a malfunction of the image forming apparatus.